Embodiments of the present invention relate generally to red-emitting phosphors, and particularly moisture-resistant red-emitting phosphors. More particularly, the invention relates to moisture-resistant K2SiF6:Mn4+, and methods of making the same.
Red-emitting phosphors based on complex fluoride materials activated by Mn4+ can be utilized in combination with yellow/green emitting phosphors such as YAG:Ce or other garnet compositions to achieve warm white light (CCTs<5000 K on the blackbody locus, color rendering index (CRI)>80) from a blue LED, equivalent to that produced by current fluorescent, incandescent and halogen lamps. These materials absorb blue light strongly and efficiently emit between about 610-635 nm with little deep red/NIR emission.
While the efficacy and CRI of lighting systems using Mn4+ doped fluoride hosts can be quite high, one potential limitation is their susceptibility to degradation under use conditions. It is possible to reduce this degradation using post-synthesis processing steps. However, development of these materials with improved performance and stability may be desirable.